The present invention relates to a display device, and particularly to a liquid crystal display device having a backlight using fluorescent materials.
In a liquid crystal display panel used for a liquid crystal display device, a TFT substrate on which pixels having pixel electrodes and thin-film transistors (TFTs) are formed in a matrix and an opposed substrate facing the TFT substrate are disposed, and liquid crystal is sandwiched between the TFT substrate and the opposed substrate. An image is formed by controlling the transmission of light by liquid crystal molecules for each pixel.
Liquid crystal display devices that are currently available in the market include some field sequential liquid crystal display devices. However, color filter liquid crystal display devices that absorb white light beams from white light sources using color filters for color display are used in many cases. The transmission of color filters tends to be decreased along with an increase in the range of color reproduction, and the color filters are a main factor for a decrease in the energy conversion efficiency in the color filter liquid crystal display devices.
As a color display method other than the color filter system, there is a method using wavelength conversion by fluorescent materials in addition to the above-described field sequential system. Specifically, blue light sources or near-ultraviolet light sources are used for light sources, and source light beams are absorbed by a wavelength conversion layer to emit fluorescence. Thus, the source light beams are converted to light beams with longer wavelengths. Fluorescent materials are used for the wavelength conversion layer, and thus the display device using the wavelength conversion by the fluorescent materials is occasionally referred to as a fluorescent material display device in the specification.
Japanese Unexamined Patent Application Publication No. 2013-246303 describes such a display device. Japanese Unexamined Patent Application Publication No. 2013-246303 describes a configuration in which a monochromatic layer containing fluorescent materials is formed for each pixel, a light-absorbing layer is formed between the monochromatic layers containing the fluorescent materials, and a reflection film is formed between the monochromatic layer containing the fluorescent materials and the light-absorbing layer.